In the field of backlights of liquid crystal displays, there has been a growing extent of products designed to pursue high image quality and high luminance by enhancing contrast by individually controlling the amounts of emission of LEDs (light-emitting diodes) through the use of local dimming driving that partially controls LEDs. There has been a demand for reductions in thickness of backlights, and in the field of direct-type backlights, there has been a demand for substantial reductions in size of LEDs. For this reason, a technique by which to mount small-sized LEDs (hereinafter referred to as “mini-LEDs”) of a very small size of, for example, 0.2 mm×0.2 mm has come into use.
In general, for higher light efficiency of LEDs, a direct-type backlight is configured such that a reflective sheet is placed on an LED substrate mounted with a plurality of LEDs and the LEDs are disposed in LED opening holes formed in the reflective sheet, with the result that light is reflected by the reflective sheet. Moreover, in the pursuit of high luminance and high image quality, there has been a demand for the prevention of a decrease in luminance that is caused by expansion and contraction of the reflective sheet. For this reason, it has been known that the reflective sheet is retained by a fixing member bored through the LED substrate to attach the reflective sheet and the LED substrate to each other and, by making an LED opening hole located farther away from the fixing member larger than an LED opening hole located closer to the fixing member, the holes in the reflective sheet are prevented from being displaced from the positions of the LEDs (PTL 1).